Size control of BaTiO3 in solid-state reaction between BaCO3 and TiO2 was demonstrated by varying the size of TiO2 and milling conditions of BaCO3. The smaller TiO2 particles had higher surface area, resulting in fast...Size control of BaTiO3 in solid-state reaction between BaCO3 and TiO2 was demonstrated by varying the size of TiO2 and milling conditions of BaCO3. The smaller TiO2 particles had higher surface area, resulting in faster initial reaction. The mechanically milled BaCO3 particles accelerated the diffusion process and decreased the calcinations temperature. It can be deduced from the results that the size control is possible and nano-sized BaTiO3 particles with about 60 nm can be synthesized by using the conventional solid-state reaction between BaCO3 and TiO2.展开更多
<span style="font-family:Verdana;">In work reported here, the dynamic properties and low-velocity impact response of woven carbon/epoxy laminates incorporating a novel 3D interlaminar reinforcement con...<span style="font-family:Verdana;">In work reported here, the dynamic properties and low-velocity impact response of woven carbon/epoxy laminates incorporating a novel 3D interlaminar reinforcement concept with dense layers of Z-axis oriented milled carbon fiber Supercomposite</span><sup><span style="font-family:Verdana;">TM</span></sup><span style="font-family:Verdana;"> prepregs, are presented. Impulse-frequency response vibration technique is used for non-destructive evaluation of the dynamic flexural modulus (stiffness) and loss factor (intrinsic damping) of woven carbon/epoxy control and Supercomposite</span><sup><span style="font-family:Verdana;">TM</span></sup><span style="font-family:Verdana;"> laminates. Low-velocity punch-shear tests were performed on control and Supercomposite</span><sup><span style="font-family:Verdana;">TM</span></sup><span style="font-family:Verdana;"> laminates according to ASTM D3763 Standard using a drop-weight impact test system. Control panels had all layers of 3K plain woven carbon/epoxy prepregs, with a dense interlaminar reinforcement of milled carbon fibers in Z-</span><span style="font-family:;" "=""> </span><span><span style="font-family:Verdana;">direction used in designing the Supercomposite</span><sup><span style="font-family:Verdana;">TM</span></sup><span style="font-family:Verdana;"> laminate—both having same areal density. Impulse-frequency response vibration experiments show that with a 50% replacement of woven carbon fabric in control panel with milled carbon fibers in Z direction dynamic flexural modulus reduced 25%</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">-</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">30% (loss in stiffness) and damping increased by about the same 25%</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">-</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">30%. Low-velocity punch-shear tests demonstrated about</span><span style="font-family:;" "=""> </span><span><span style="font-family:Verdana;">25% reduction in energy absorption for Supercomposite</span><sup><span style="font-family:Verdana;">TM</span></sup><span style="font-family:Verdana;"> laminates with the replacement of 50% woven carbon fabric in control panel.</span></span>展开更多
采用固相剪切碾磨(S^3M)技术并结合冷冻粉碎制备了适于选择性激光烧结(SLS)的尼龙12(PA12)/多壁碳纳米管(CNTs)复合粉体及相应的烧结制品。采用激光粒度分析仪、扫描电镜、透射电镜、动态力学分析、傅里叶变换红外光谱分析、差示扫描量...采用固相剪切碾磨(S^3M)技术并结合冷冻粉碎制备了适于选择性激光烧结(SLS)的尼龙12(PA12)/多壁碳纳米管(CNTs)复合粉体及相应的烧结制品。采用激光粒度分析仪、扫描电镜、透射电镜、动态力学分析、傅里叶变换红外光谱分析、差示扫描量热仪等对所得PA12/CNTs复合粉体和相应SLS制品的结构与性能进行了表征。结果表明,固相剪切碾磨-冷冻粉碎制备的复合粉体颗粒以椭球形为主,平均粒径75μm,SLS加工窗口为10℃左右,满足SLS对被烧结材料的性能要求,通过加入质量分数为0.1%的流动助剂纳米SiO_2能进一步改善复合粉体的SLS加工性能。磨盘碾磨通过其强大的三维剪切力场实现了CNTs的切割及在PA12基体中的良好分散以及CNTs与PA12大分子链的接枝,显著改善了二者之间的界面相容性。此外,通过优化SLS加工参数,成功制备了表面平整、结构复杂、性能良好的PA12/CNTs烧结制品。所得PA12/CNTs烧结样品具有优良的力学性能,拉伸强度达到44.2 MPa,缺口冲击强度达到8.12 k J/m^2。展开更多
文摘Size control of BaTiO3 in solid-state reaction between BaCO3 and TiO2 was demonstrated by varying the size of TiO2 and milling conditions of BaCO3. The smaller TiO2 particles had higher surface area, resulting in faster initial reaction. The mechanically milled BaCO3 particles accelerated the diffusion process and decreased the calcinations temperature. It can be deduced from the results that the size control is possible and nano-sized BaTiO3 particles with about 60 nm can be synthesized by using the conventional solid-state reaction between BaCO3 and TiO2.
文摘<span style="font-family:Verdana;">In work reported here, the dynamic properties and low-velocity impact response of woven carbon/epoxy laminates incorporating a novel 3D interlaminar reinforcement concept with dense layers of Z-axis oriented milled carbon fiber Supercomposite</span><sup><span style="font-family:Verdana;">TM</span></sup><span style="font-family:Verdana;"> prepregs, are presented. Impulse-frequency response vibration technique is used for non-destructive evaluation of the dynamic flexural modulus (stiffness) and loss factor (intrinsic damping) of woven carbon/epoxy control and Supercomposite</span><sup><span style="font-family:Verdana;">TM</span></sup><span style="font-family:Verdana;"> laminates. Low-velocity punch-shear tests were performed on control and Supercomposite</span><sup><span style="font-family:Verdana;">TM</span></sup><span style="font-family:Verdana;"> laminates according to ASTM D3763 Standard using a drop-weight impact test system. Control panels had all layers of 3K plain woven carbon/epoxy prepregs, with a dense interlaminar reinforcement of milled carbon fibers in Z-</span><span style="font-family:;" "=""> </span><span><span style="font-family:Verdana;">direction used in designing the Supercomposite</span><sup><span style="font-family:Verdana;">TM</span></sup><span style="font-family:Verdana;"> laminate—both having same areal density. Impulse-frequency response vibration experiments show that with a 50% replacement of woven carbon fabric in control panel with milled carbon fibers in Z direction dynamic flexural modulus reduced 25%</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">-</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">30% (loss in stiffness) and damping increased by about the same 25%</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">-</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">30%. Low-velocity punch-shear tests demonstrated about</span><span style="font-family:;" "=""> </span><span><span style="font-family:Verdana;">25% reduction in energy absorption for Supercomposite</span><sup><span style="font-family:Verdana;">TM</span></sup><span style="font-family:Verdana;"> laminates with the replacement of 50% woven carbon fabric in control panel.</span></span>
文摘采用固相剪切碾磨(S^3M)技术并结合冷冻粉碎制备了适于选择性激光烧结(SLS)的尼龙12(PA12)/多壁碳纳米管(CNTs)复合粉体及相应的烧结制品。采用激光粒度分析仪、扫描电镜、透射电镜、动态力学分析、傅里叶变换红外光谱分析、差示扫描量热仪等对所得PA12/CNTs复合粉体和相应SLS制品的结构与性能进行了表征。结果表明,固相剪切碾磨-冷冻粉碎制备的复合粉体颗粒以椭球形为主,平均粒径75μm,SLS加工窗口为10℃左右,满足SLS对被烧结材料的性能要求,通过加入质量分数为0.1%的流动助剂纳米SiO_2能进一步改善复合粉体的SLS加工性能。磨盘碾磨通过其强大的三维剪切力场实现了CNTs的切割及在PA12基体中的良好分散以及CNTs与PA12大分子链的接枝,显著改善了二者之间的界面相容性。此外,通过优化SLS加工参数,成功制备了表面平整、结构复杂、性能良好的PA12/CNTs烧结制品。所得PA12/CNTs烧结样品具有优良的力学性能,拉伸强度达到44.2 MPa,缺口冲击强度达到8.12 k J/m^2。